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Corrugated Stainless Steel Tubing (CSST) for Gas Distribution

An alternative to traditional threaded black-iron gas piping

Corrugated stainless steel tubing is light and flexible with a yellow PVC covering and metal fittings.

Also see: Corrugated Stainless Steel Tubing for Fuel Gas Distribution in Buildings and Concerns over Lightning(PDF)

Corrugated stainless steel tubing (CSST) is a promising alternative to traditional threaded black-iron gas piping for residential, commercial and industrial applications. Its light weight, flexibility, and need for fewer connections and fittings can make it easier to install than traditional threaded black-iron piping. These benefits can add up to substantial labor savings for installers and cost savings for builders.

Since 1989 over 150 million feet has been installed in residential, commercial, and industrial structures. During 2002, approximately 45 million feet of CSST was sold and installed in the U. S. - an indication of the rapid increase in use of CSST in recent years.

Corrugated stainless steel gas tubing (CSST) consists of a continuous, flexible, stainless steel pipe with an exterior PVC covering. The piping is produced in coils that are air-tested for leaks. It is most often installed in a central manifold configuration (also called parallel configuration) with "home run" lines that extend to gas appliances. Flexible gas piping is lightweight and requires fewer connections than traditional gas piping because it can be bent easily and routed around obstacles.

The multiport manifold allow for easy, future expansion of the system for room additions or additional appliances. CSST has the potential for higher levels of system safety because connections and joints behind the wall, common in black iron pipe, are essentially eliminated. In addition, builders and installers have noted a reduction in employee injuries by eliminating the heavy equipment and apparatus associated with traditional black iron pipe installations.


Affordability

Depending on the setup, and lower labor costs, CSST can cost less than typical threaded pipe.

Quality and Durability

CSST is very strong, flexible, and can withstand high pressures. This allows for a safer and better performing gas home.

Safety and Disaster Mitigation

Because of its high quality and the fact that there are less joints for a CSST pipe run than in threaded pipe, there is less of a chance for gas leaks.


Easy

Stainless steel gas piping is available in most parts of the country through distributors, but in many instances it is not carried in stock and must be shipped. Stainless steel piping material and fittings cost more than conventional threaded black iron pipe for distributing natural gas. A lack of familiarity by code officials may present problems. (The proprietary nature of the fittings and tools may also increase costs).


According to the Gas Research Institute, labor savings can range from one-quarter to two-thirds on new construction projects and almost three-quarters on remodeling projects.

Although the material cost for CSST pipe and fittings is higher than conventional black iron, the labor cost savings may make up for the higher material cost.

According to PM Engineer (August 29, 2000), in the majority of instances, the installed cost of CSST is lower than the installed cost of conventional black-iron threaded pipe. There are cases, however, where the installed cost of CSST will be higher. For example, if two or three gas appliances are located in close proximity, it may be less expensive to install conventional gas pipe. However, if gas appliances are spread throughout the house, it will likely cost less to install CSST.


Not Applicable


Stainless steel gas piping is approved by all national plumbing and gas codes. However, in isolated areas, local jurisdictions and authorities may restrict the use of CSST pipe.

CSST is regulated by American National Standards Institute ANSI/IAS LC 1-1997/CSA 6.26-M97 Fuel Gas Piping Systems Using Corrugated Stainless Steel Tubing (CSST). The standard requires that a contractor be certified before installing CSST.

A lack of familiarity by code officials may present problems.


Model reMODEL: Philadelphia, Pennsylvania


Stainless steel gas piping is installed using specialty fittings and cutting tools. Connections can be made in minutes with the correct tools. Striker plates must be installed where the gas lines penetrate wall studs to protect lines from puncture during drywall installation. Typical installation of a flexible gas piping system for a single-family unit can be completed in one day.

CSST length is continuously marked on the pipe for ease of measuring and cutting.

CSST cannot be installed in direct contact with the ground.


Some manufacturers warrant their CSST and fitting for a period of one year after installation.

There have been reports of fires caused by lightning strikes near homes with CSST flexible gas piping. The root cause of these fires has been attributed to either a lack of or inadequate bonding of the CSST which has resulted in arcing damage to the tubing. This problem resulted in a class action law suit involving four CSST manufacturers: Omegaflex (TRACPIPE or COUNTERSTRIKE); Parker-Hannifin Corp. (PARFLEX); Titeflex Corp. (GASTITE); and Wward Manufacturing, Inc. (WARDFLEX). The parties to the suit have signed a Settlement Agreement that provides class members with a partial to full financial reimbursement for either a lightning protection system or upgraded bonding of their existing CSST system. For further information on the Settlement Agreement, visit www.CSSTsettlement.com; call the Administrator at 1-800-420-2916; or write to the CSST Settlement Administrator at P.O. Box 4349, Portland, OR 97208-4349.

Also see the following white paper for more information: Corrugated Stainless Steel Tubing for Fuel Gas Distribution in Buildings and Concerns over Lightning (PDF).


Corrugated stainless steel piping eliminates the need for carrying and threading heavy pipe. Because of its flexibility, it can be pulled in a manner similar to electrical wire. With fewer fittings than threaded pipe, the potential for leaks is reduced. Stainless steel gas piping is easy to expand and to use in retrofits where frequent bends and turns are necessary. CSST is rated for high pressure. When used at higher pressure, the pipe size, and therefore material cost, can be decreased.

Disclaimer: The information on the system, product or material presented herein is provided for informational purposes only. The technical descriptions, details, requirements, and limitations expressed do not constitute an endorsement, approval, or acceptance of the subject matter by the NAHB Research Center. There are no warranties, either expressed or implied, regarding the accuracy or completeness of this information. Full reproduction, without modification, is permissible.